Automatic water gate



Dec. 11, 1934.

J. C; STEVENS AUTOMATIC WATER GATE Filed Jan. 14, 1933 2 Sheets-Sheet 1 Dec. 11, 1934. c STEVENS AUTOMATIC WATER GATE Filed Jan 14, 1933 2 Sheets-Sheet 2 til Patented Dec. 11, 193 4 UNITED STATES "PATENT OFFICE AUTOMATIC WATER GATE John Cyprian Stevens, Portland, Oreg. Application January 14, 1933, Serial No. 651,665 6 Claims. (01. .61-25) My invention relates to improvements in automatic water gates; and the object of my invention is the control of the level of water in forebays, reservoirs, canals, or other water holding structures, and the maintenance of a constant predetermined. water level therein. The term water used herein is intended to include any other liquid.

I attain these objects bythe devices, mechanisms and arrangement of parts illustrated in the accompanying drawings in which:

Figure l is a side View of the piers, gate and mechanism. Figure 2 is a view of the gate and mechanism looking upstream. Figure 3 shows a detail or" the water seal. Figure i is an alternate arrangement of the gate and mechanism. Figure 5 is a half-section along M-N. of Figure 4. Similar numbers refer to similar parts throughout.

The invention comprises essentially a gate leaf hinged at the top to swing downstream and balanced against the water pressure by a moveable counterweight. -It is placed in an opening in the wall of a reservoir, canal, forebay or .any other structure'through which water passes.

In the drawings, 1 represents the piers, 2 a sill between the piers. These may be built of any suitable material such as concrete ortimber. The piers may be tied together at the top by a deck 3. It is not necessary that the gate fill the upper portion of the frame, since the gate leafneed only extend above high water level.

As used herein the term gate will include the leaf, the hangers, track for the counterweight and bracing; the term gate-frame will include the portion of the piers, sill and deck that forms the openinginwhich the gate hangs.

The gate consists of a leaf 4, of wood, steel .or other suitable material, supported by two or more hangers 5, hung from the deck or top of the piers by a hinge 6, which permits the gate to swing in a downstream direction. Fastened to the gate hangers 5 are two tracks 7, on either side of the gate leaf extending downstream and held rigidly in position by braces 8 and 9.

The gate leaf projects slightly over the face of the gate frame in order to effect a water seal when the gate is closed. The sill and piers are recessed at the edge of the waterway (Figure 3). In this recess is a rubber staunching strip 10 held by a metal strip 11 fastened to sill and piers by screws in wooden plugs 12, or by other suitable means. On the gate leaf is a metal bar 13, with a bulb on one edge so positioned that the bulb presses against the rubber staunching strip as the gate closes. The metal strip 11 forms a stop for the gate leaf so that the bulb can not crush too deeply into and distort or injure the rubber staunching strip and thus destroy its water sealing properties. At the corners the rubber staunching strip and the metal strip are bent to a small. radius around the corner and the bulb bar on the gate leaf is similarly bent so that the seal is not broken throughout its entire peripheral length. The seal extends along the bottom and the sides of the gate to above high water level.

A counterweight 14 made of lead, concrete, or other suitable-material is supported on sheaves 15, which run on the tracks '7. The position of this counterweight is determined by a pair of links 16, whose length may be adjusted (adjustable feature not shown). Each link has one end pivotal-1y attached to the counterweight at the shaft of a .sheave 1'7 and the other end pivotally fixed to a bearing .18 fastened to the gate frame in sucha manner that the gate may swing outward between the links. Each bearing may consist .of an angle 19 with .a series of holes in one leg, and the link may end in a yoke 20 straddling the legand be positioned in any one of the holes by'means of a short bolt.

It is obvious that as thegate opens the counterweight .14 will be pulled by the links 16 nearer the vertical plane through the hinge and simultaneously will transfer a portion of its weight from the tracks through the links to the bearings on the gate-frame. It is also obvious that only thatportion 0f the counterweight resting on the tracks serves to balance the water pressure on the-gate.

In-the closed position the water pressure on the upstream face of the gate may be represented by a force P acting at a distance b from the hinge (Figure 1) This .pressure is resisted by two other forces; the weight W acting at a distance a from the hinge, and the reaction of the gateframe against the gate. As the water rises the reaction-of the gate-frame becomes less and less, finally becoming zero when the moments of the water pressure P and weight W about the hinge are equal. If the water continues to rise the moment of the water pressure becomes greater than the moment of the counterweight and the gate starts to open.

The water flows out the open space between the edges of the gate leaf and the gate-frame. As soon as flow starts the pressure on the gate diminishes from three causes: first, some of the pressure head is converted into velocity head, second, there is established a drop down surface curve S (Figure l) to the water just upstream from the gate which reduces the head at the gate and consequently the pressure on it; and, third, by being rotated about its hinge above the water surface the gate leaf is slightly lifted out of the prism of outflowing water. Simultaneously with the opening of the gate the moment of the counterweight about the hinge has also been correspondingly decreased by two processes: first, the counterweight is pulled by the links nearer the hinge, thus shortening the moment-arm, and, second, the inclination to the horizontal of the track supporting the weight has been increased so that a portion of the weight formerly supported on the track is transferred through the links to the bearings on the gateframe, thus reducing the component of the counterweight on the gate.

The combined effect of these factors is that after the water has risen above a certain predetermined level the water pressure causes the gate to open and the process of opening so positions the counterweight relative to the gate and simultaneously alters its weight component on the gate that the moment of the counterweight about the gate hinge equals the moment of the water pressure about the same point, thus establishing a balance of forces. The water pressure acting through the distance the gate moves performs the work of adjusting the counterweight to balance that water pressure. If the water surface falls but is still above that certain predeterminedlevel, the new water pressure effects a new adjustment establishing a balance of forces at a different gate opening. If the water drops to that predetermined level, the gate closes completely. These processes serve to maintain a water level within any water holding structure that is practically constant. Tests have shown that the gate will respond to changes in water levels of between 1 and 2 per cent of the head on the gate sill. Obviously even greater sensitiveness may be secured by refinements in design and construction.

The dotted outlines in Figures 1 and 4 show the gate partly open. Note that the momentarm of the counterweight has been decreased from a to a (see Figure 1) and that the counterweight 14 in its dotted line position is being supported partly on the track 7 and partly on the links 16, thus reducing the counterbalancing weight from W to some lesser value W.

In Figures 1 and 2 the links 16 are straight and cross the opening through which the water pours when the gate is open. Under some conditions this might not be desirable. Figures 4 and 5 show an alternate arrangement that eliminates this feature. The links 16 are formed into an angle and thus avoid intersecting the prism of outfiowing water. The angle links move in recesses 21 in the piers 1.

The track 7 may be positioned anywhere between the hinge and the bottom of the gate. The counterweight may be light with a long momentarm or heavy with a short arm. The links 16 may have their fixed bearings positioned at any desired point on pier, sill or floor and their length may be varied. These several factors give endless elasticity to the gate design so that the moment of the counterweight may be made to automatically adjust itself equal to the moment of the water pressure for a wide range of water level fluctuations and gate openings.

The gate and mechanism herein described have been tested in a hydraulic laboratory. Automatic adjustment is an established fact. The gate automatically adjusts its opening to a wide variation of flow. It maintains a given position without oscillations, and is sensitive to slight variations of water levels. It may be used in a fiume, on the crest of dams, on level or inclined floors, under a great variety of physical conditions. It operates with equal accuracy under free water conditions or when partly submerged.

Only basic principles have been outlined herein. Details of design and adjustment to meet any given set of conditions may be infinitely va ried without departing from the spirit and scope of my invention.

I claim:

1. An automatic water gate comprising a gate leaf hinged at the top and actuated by water pressure to swing with respect to an opening in the Wall of a water holding structure, a counterweight movably supported on tracks attached to the gate, and means on the gate frame connected with the counterweight for moving the counterweight on said tracks toward the gate-leaf as the gate opens and from the gate-leaf as it closes.

2. In an automatic water gate, the combination of a gate hinged at the top to swing in an opening in the wall of a water-holding structure, a pair of tracks attached to the gate, a counterweight carried by and moveable on the tracks, and a pair of links pivotally connecting the counterweight to fixed bearings on the gate frame that moves the counterweight relative to the gate and varies its weight-component on the gate as the gate is moved by the water pressure against it.

3. In an automatic water gate, the combination of a gate hinged at the top to swing in a frame or opening in the wall of a water-holding structure, a pair of tracks attached to the gate, a counterweight supported on sheaves running on the tracks, and a pair of links so positioned that the gate may swing between them, each link having one end pivotally attached to the counterweight and the other end pivotally attached to a fixed bearing on the gate-frame independent of and not moving with the gate. I

4. In an automatic water gate, the combination of a gate hinged at the top, a pair of tracks attached to the gate, a counterweight supported movably on the tracks, a pair of links pivotally attached to the counterweight and to bearings on the gate frame, and a water seal along the pe riphery of the gate between the gate and its frame.

5. In an automatic water gate, the combination of a gate hinged at the top, a pair of tracks attached to the gate, a counterweight attached movably on the tracks, a pair of links pivotally attached to the gate frame and to the counterweight, and a water seal consisting essentially of a rubber staunching strip attached to the gateframe and curved around the corners of the frame, a metal bar with a bulb on one edge attached to the gate, leaf and curved around the corners of the leaf to press against the rubber staunching strip at all points, and a stop for the gate leaf to prevent the bulb from distorting and injuring the rubber staunching strip.

6. A gravity closable water gate comprising a gate leaf swingable about a substantially horizontal axis above the effective center of gravity of the leaf, a support mounted on the leaf and a weight mounted on the support for movement toward and away from the plane of the leaf, and means connecting the weight to a relatively fixed point on the structure so that the weight will be moved relative to the plane when the gate leaf swings.

J. C. STEVENS. 

